The present invention relates generally to structures for resisting opposed directional forces, such as press frames, and more particularly to structures of this type which are constructed without castings or weldments.
Force-resisting structures have forces applied thereto by external actuating mechanisms which may be hydraulic or mechanical, for example. Such a structure may include one or more large castings or may comprise an assembly of components, and the components of that assembly, or of subassemblies thereof, are often joined together by welding.
Force-resisting structures, such as press frames, require a certain amount of machining on various surfaces thereof. When the structure is a casting or a heavy weldment, large machining equipment, not available at many manufacturing facilities, must be employed.
A force-resisting structure composed of a number of smaller components welded together into an assembly has other significant problems. Care must be taken that the weld areas are not highly stressed, and the finished structure must often be machined after welding to remove the effects of distortion which can occur during the welding process. Machining the finished structure, after all the components have been welded together, involves handling difficulties and requires large machining equipment not available in many manufacturing facilities. Moreover, welded structures can also undergo metallurgical changes in the area of the weld that adversely affect the metal there and which may require further processing, such as heat treating, to offset such adverse effects.
Another expedient employed in producing force-resisting structures is a so-called "tie rod" construction, but this expedient requires special procedures to pre-stress the tie rods, reduce mechanical deflections and retain certain constituent members in the desired condition of stress.